Highly Enantioselective Iridium-Catalyzed Hydrogenation of α,β-Unsaturated Esters
作者:Jia-Qi Li、Xu Quan、Pher G. Andersson
DOI:10.1002/chem.201200907
日期:2012.8.20
α,β‐Unsaturated esters have been employed as substrates in iridium‐catalyzed asymmetric hydrogenation. Full conversions and good to excellent enantioselectivities (up to 99 % ee) were obtained for a broad range of substrates with both aromatic‐ and aliphatic substituents on the prochiral carbon. The hydrogenated products are highly useful as building blocks in the synthesis of a variety of natural
The synthesis of non-racemic β-alkyl-β-aryl-disubstituted allyl alcohols and their transformation into allylamines and amino acids bearing a quaternary stereocenter
synthesis of non-racemic β-alkyl-β-aryl allyl alcohols and their transformation into allylamines bearing a quaternary stereogenic center is reported. The allyl alcohols were prepared either by Cu-catalyzed enantioselective reduction of enones or by sequential alkylation/hydrostannylation/Stille coupling of non-racemic propargyl alcohols. The prepared β-alkyl-β-aryl allyl alcohols were converted (after carbamoylation)
improved generation of chiral cationic iridium catalysts for the asymmetricisomerization of primaryallylicalcohols is disclosed. The design of these air‐stable complexes relied on the preliminary mechanistic information available, and on Charton analyses using two preceding generations of iridium catalysts developed for this highly challenging transformation. Sterically unbiased chiral aldehydes
作者:Francesco G. Gatti、Fabrizio Antonietti、Elisabetta Brenna、Claudio Fuganti、Tommaso Giovenzana、Valentina Grande、Luciana Malpezzi
DOI:10.1055/s-2005-861856
日期:——
A lipase-mediated synthesis of all four enantiomers of isoaminile is reported. The key issues of the paper are: (i) enantioselective acetylation of allylic alcohol (E)-(′)-5 to give (E,S)-5 (ee = 92%) and (E,R)-6 (ee >99%); (ii) Claisen-Johnson rearrangement of R and S enantiomers of 5 to generate the quaternary benzylic stereocenter; (iii) chromatographic separation of aldehyde diastereoisomers; (iv)
报告了异胺的所有四种对映异构体的脂肪酶介导的合成。该论文的关键问题是:(i)烯丙醇(E)-(')-5的对映选择性乙酰化得到(E,S)-5(ee = 92%)和(E,R)-6(ee >99%);(ii) 5 的 R 和 S 对映异构体的 Claisen-Johnson 重排以产生季苄基立体中心;(iii) 醛类非对映异构体的色谱分离;(iv) 醛 (2R,4R)-10 的 X 射线结构;(v) 在 11 的水解过程中意外形成内酯 12。
Ruthenium-Catalyzed Oxidation of Allyl Alcohols with Intermolecular Hydrogen Transfer: Synthesis of α,β-Unsaturated Carbonyl Compounds
Ruthenium-catalyzed oxidation of multisubstituted allyl alcohols in the presence of benzaldehyde gives enals or enones in good yields. Unlike the commonly reported ruthenium-catalyzed isomerization reaction of allyl alcohols to give saturated ketones, an intermolecular rather than intramolecular hydrogen transfer is involved in this transformation. This reaction offers an efficient, mild, and high-yielding